This protocol is designed to measure the reliability of a questionnaire and interview method developed to assess food intake in epidemiologic studies of cancer in Anglos (White, non-Hispanic), Blacks, and Hispanics, and the applicability of these methods in the field study setting. The questionnaire is structured to obtain the intake frequency of a comprehensive list of food items one year previous to interview. A nutrient data base will be utilized to compute the total amount of consumption per year of different nutrients that are considered relevant to cancer. To determine if it is possible to shorten and facilitate the interview, the use of food flash cards will be compared to standard interview methods for completing the food frequency list. Four groups of subjects from each of the three ethnic groups will be interviewed twice. Computed nutrient intake levels will be ued to evaluate the repeatability of the same method, and to compare data gathered with and without the use of picture cards. Case-comparison studies of nutrition relative to cancer pose special problems as current diet is likely not the same as that previous to disease development, diagnosis and treatment. In addition, diet reported in the recent past may not be representative of earlier patterns, which is important considering the nature of carcinogenic promoters, initiators and antagonists. To study the reliability of asking people about their diet in the recent past, three additional groups of Anglos, Blacks, and Hispanics will be interviewed regarding their current diet and reinterviewed one year later with respect to their diet one year past. To evaluate the consistency of dietary intake over a lifetime, all respondents will be asked to report significant diet changes. Interviewers will then probe about such changes using inquiries about major life change events. The necessity of collecting information about serving size will be addressed in the analysis. The gain in information through the use of estimated serving sizes will be weighed against the practice of assuming a standard amount of each food item.